Set Camera Depth of Field so that the character is not blurry, but the scene behind it is
Depth of field is the area in which elements are acceptably in focus. Objects closer of further away from that area will be progressively blurry.

Image from https://expertphotography.com/understanding-depth-of-field-photography/
By changing the focus and the $f$ stop (iris) on the camera, you can determine where objects are in focus and when they are not. The wider (lower value) on the $f$ stop, focus will be more critical. As you close (higher value) the iris to a higher $f$ stop more of the scene (in front and behind the object) will be in focus, or less blurry.
Here's an example from wikipedia:

Play with the values for focus and $f$ stop, until you find the point where you get the results you are after.